The present invention relates to an apparatus for singling flat material to be conveyed having a suction device, with apertures or openings in the suction device defining an area within which the suction device grasps the material to be singled.
Devices for singling flat material to be conveyed having a suction drum as a suction device, as known e.g. from DE 29 05 278 C3, consist substantially of a stator and rotor. The stator has sectorial suction chambers extending in the circumferential direction which are subjected to underpressure. The rotor has suction openings which are each associated with the suction chambers of the stator and remove the material singly from a stack and feed it to a following transport system. The material to be singled is grasped within a rotation angle of the rotating rotor within which the suction chambers of the stator are congruent with the associated suction openings of the rotor, i.e. stator and rotor work on the so-called rotary valve principle. The suction openings of the rotor are usually located along a surface line of the rotor and activated or opened simultaneously. The suction openings can also be slightly shifted from the surface line so as to be opened successively with a small time delay during rotation of the rotor, thereby preventing the material to be singled from being set on a slant. It is likewise known to dispose a plurality of suction openings one behind the other in the sectorial direction which are activated successively during rotation of the rotor so that a plurality of suction openings of the rotor in the sectorial direction are simultaneously active as long as they are in the area of the suction chambers of the stator.
Flat material to be conveyed refers in particular to bank notes, vouchers, data carriers and sheets of paper.
However, known singling devices have in particular the disadvantage that operation of the suction device produces a high noise level which is perceived as very unpleasant. The noise produced by the suction device is caused mainly by the activation of the suction openings. Further noise components result from the material to be conveyed hitting or slapping against the suction device when said material is removed from the stack for singling.
The present invention is therefore to state an apparatus for singling flat material to be conveyed having a suction device wherein at least the noise produced by the suction openings during operation is lowered so that the resultant noise level is reduced.
The problem is solved according to the novel features of the invention.
The invention includes a suction device having a plurality of openings formed along the periphery of the rotor such that the openings are arranged in rows in an alternating, staggered relationship to thereby generate an inverse pressure profile between alternating rows and a time shifted activation of the openings to partially eliminate noise produced from activation of the openings.
Further advantages of the present invention result from the dependent claims and the following description of embodiments with reference to figures. The figures show only the components relevant for understanding the present invention. The same components in different figures have the same reference signs.